1.1 --- a/xen/arch/x86/domain.c	Tue Apr 06 07:16:47 2010 +0100
     1.2 +++ b/xen/arch/x86/domain.c	Wed Apr 07 08:09:00 2010 +0100
     1.3 @@ -1442,7 +1442,8 @@ void context_switch(struct vcpu *prev, s
     1.4  
     1.5      set_current(next);
     1.6  
     1.7 -    if ( (per_cpu(curr_vcpu, cpu) == next) || is_idle_vcpu(next) )
     1.8 +    if ( (per_cpu(curr_vcpu, cpu) == next) ||
     1.9 +         (is_idle_vcpu(next) && cpu_online(cpu)) )
    1.10      {
    1.11          local_irq_enable();
    1.12      }

     2.1 --- a/xen/arch/x86/smpboot.c	Tue Apr 06 07:16:47 2010 +0100
     2.2 +++ b/xen/arch/x86/smpboot.c	Wed Apr 07 08:09:00 2010 +0100
     2.3 @@ -997,17 +997,13 @@ static int __devinit do_boot_cpu(int api
     2.4  	return boot_error;
     2.5  }
     2.6  
     2.7 -static void idle_task_exit(void)
     2.8 -{
     2.9 -	/* Give up lazy state borrowed by this idle vcpu */
    2.10 -	__sync_lazy_execstate();
    2.11 -}
    2.12 -
    2.13  void cpu_exit_clear(void)
    2.14  {
    2.15  	int cpu = raw_smp_processor_id();
    2.16  
    2.17 -	idle_task_exit();
    2.18 +	/* Previous non-idle state should be synchronised already. */
    2.19 +	if (__sync_lazy_execstate())
    2.20 +		BUG();
    2.21  
    2.22  	cpucount --;
    2.23  	cpu_uninit();
    2.24 @@ -1302,6 +1298,13 @@ int __cpu_disable(void)
    2.25  
    2.26  	remove_siblinginfo(cpu);
    2.27  
    2.28 +	/*
    2.29 +	 * If we are running the idle vcpu, sync last non-idle vcpu's state
    2.30 +	 * before changing cpu_online_map. If we are running non-idle vcpu,
    2.31 +	 * we will synchronously sync the state in context_switch() later.
    2.32 +	 */
    2.33 +	__sync_lazy_execstate();
    2.34 +
    2.35  	/* It's now safe to remove this processor from the online map */
    2.36  	cpu_clear(cpu, cpu_online_map);
    2.37  	fixup_irqs();